/*
 * Copyright (c) 2000 World Wide Web Consortium,
 * (Massachusetts Institute of Technology, Institut National de
 * Recherche en Informatique et en Automatique, Keio University). All
 * Rights Reserved. This program is distributed under the W3C's Software
 * Intellectual Property License. This program is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE.
 * See W3C License http://www.w3.org/Consortium/Legal/ for more details.
 */
using System;

namespace org.w3c.dom
{

    /**
     * The <code>Element</code> interface represents an element in an HTML or XML 
     * document. Elements may have attributes associated with them; since the 
     * <code>Element</code> interface inherits from <code>Node</code>, the 
     * generic <code>Node</code> interface attribute <code>attributes</code> may 
     * be used to retrieve the set of all attributes for an element. There are 
     * methods on the <code>Element</code> interface to retrieve either an 
     * <code>Attr</code> object by name or an attribute value by name. In XML, 
     * where an attribute value may contain entity references, an 
     * <code>Attr</code> object should be retrieved to examine the possibly 
     * fairly complex sub-tree representing the attribute value. On the other 
     * hand, in HTML, where all attributes have simple string values, methods to 
     * directly access an attribute value can safely be used as a convenience.In 
     * DOM Level 2, the method <code>normalize</code> is inherited from the 
     * <code>Node</code> interface where it was moved.
     * <p>See also the <a href='http://www.w3.org/TR/2000/REC-DOM-Level-2-Core-20001113'>Document Object Model (DOM) Level 2 Core Specification</a>.
     */
    public interface Element : Node
    {
        /**
         * The name of the element. For example, in: 
         * <pre> &lt;elementExample 
         * id="demo"&gt; ... &lt;/elementExample&gt; , </pre>
         *  <code>tagName</code> has 
         * the value <code>"elementExample"</code>. Note that this is 
         * case-preserving in XML, as are all of the operations of the DOM. The 
         * HTML DOM returns the <code>tagName</code> of an HTML element in the 
         * canonical uppercase form, regardless of the case in the source HTML 
         * document. 
         */
        String getTagName();

        /**
         * Retrieves an attribute value by name.
         * @param nameThe name of the attribute to retrieve.
         * @return The <code>Attr</code> value as a string, or the empty string 
         *   if that attribute does not have a specified or default value.
         */
        String getAttribute(String name);

        /**
         * Adds a new attribute. If an attribute with that name is already present 
         * in the element, its value is changed to be that of the value 
         * parameter. This value is a simple string; it is not parsed as it is 
         * being set. So any markup (such as syntax to be recognized as an 
         * entity reference) is treated as literal text, and needs to be 
         * appropriately escaped by the implementation when it is written out. 
         * In order to assign an attribute value that contains entity 
         * references, the user must create an <code>Attr</code> node plus any 
         * <code>Text</code> and <code>EntityReference</code> nodes, build the 
         * appropriate subtree, and use <code>setAttributeNode</code> to assign 
         * it as the value of an attribute.
         * <br>To set an attribute with a qualified name and namespace URI, use 
         * the <code>setAttributeNS</code> method.
         * @param nameThe name of the attribute to create or alter.
         * @param valueValue to set in string form.
         * @exception DOMException
         *   INVALID_CHARACTER_ERR: Raised if the specified name contains an 
         *   illegal character.
         *   <br>NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
         */
        void setAttribute(String name,
                                 String value);//                             throws DOMException;

        /**
         * Removes an attribute by name. If the removed attribute is known to have 
         * a default value, an attribute immediately appears containing the 
         * default value as well as the corresponding namespace URI, local name, 
         * and prefix when applicable.
         * <br>To remove an attribute by local name and namespace URI, use the 
         * <code>removeAttributeNS</code> method.
         * @param nameThe name of the attribute to remove.
         * @exception DOMException
         *   NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
         */
        void removeAttribute(String name);//                                throws DOMException;

        /**
         * Retrieves an attribute node by name.
         * <br>To retrieve an attribute node by qualified name and namespace URI, 
         * use the <code>getAttributeNodeNS</code> method.
         * @param nameThe name (<code>nodeName</code>) of the attribute to 
         *   retrieve.
         * @return The <code>Attr</code> node with the specified name (
         *   <code>nodeName</code>) or <code>null</code> if there is no such 
         *   attribute.
         */
        Attr getAttributeNode(String name);

        /**
         * Adds a new attribute node. If an attribute with that name (
         * <code>nodeName</code>) is already present in the element, it is 
         * replaced by the new one.
         * <br>To add a new attribute node with a qualified name and namespace 
         * URI, use the <code>setAttributeNodeNS</code> method.
         * @param newAttrThe <code>Attr</code> node to add to the attribute list.
         * @return If the <code>newAttr</code> attribute replaces an existing 
         *   attribute, the replaced <code>Attr</code> node is returned, 
         *   otherwise <code>null</code> is returned.
         * @exception DOMException
         *   WRONG_DOCUMENT_ERR: Raised if <code>newAttr</code> was created from a 
         *   different document than the one that created the element.
         *   <br>NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
         *   <br>INUSE_ATTRIBUTE_ERR: Raised if <code>newAttr</code> is already an 
         *   attribute of another <code>Element</code> object. The DOM user must 
         *   explicitly clone <code>Attr</code> nodes to re-use them in other 
         *   elements.
         */
        Attr setAttributeNode(Attr newAttr);//                                 throws DOMException;

        /**
         * Removes the specified attribute node. If the removed <code>Attr</code> 
         * has a default value it is immediately replaced. The replacing 
         * attribute has the same namespace URI and local name, as well as the 
         * original prefix, when applicable.
         * @param oldAttrThe <code>Attr</code> node to remove from the attribute 
         *   list.
         * @return The <code>Attr</code> node that was removed.
         * @exception DOMException
         *   NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
         *   <br>NOT_FOUND_ERR: Raised if <code>oldAttr</code> is not an attribute 
         *   of the element.
         */
        Attr removeAttributeNode(Attr oldAttr);//                                    throws DOMException;

        /**
         * Returns a <code>NodeList</code> of all descendant <code>Elements</code> 
         * with a given tag name, in the order in which they are encountered in 
         * a preorder traversal of this <code>Element</code> tree.
         * @param nameThe name of the tag to match on. The special value "*" 
         *   matches all tags.
         * @return A list of matching <code>Element</code> nodes.
         */
        NodeList getElementsByTagName(String name);

        /**
         * Retrieves an attribute value by local name and namespace URI. HTML-only 
         * DOM implementations do not need to implement this method.
         * @param namespaceURIThe namespace URI of the attribute to retrieve.
         * @param localNameThe local name of the attribute to retrieve.
         * @return The <code>Attr</code> value as a string, or the empty string 
         *   if that attribute does not have a specified or default value.
         * @since DOM Level 2
         */
        String getAttributeNS(String namespaceURI,
                                     String localName);

        /**
         * Adds a new attribute. If an attribute with the same local name and 
         * namespace URI is already present on the element, its prefix is 
         * changed to be the prefix part of the <code>qualifiedName</code>, and 
         * its value is changed to be the <code>value</code> parameter. This 
         * value is a simple string; it is not parsed as it is being set. So any 
         * markup (such as syntax to be recognized as an entity reference) is 
         * treated as literal text, and needs to be appropriately escaped by the 
         * implementation when it is written out. In order to assign an 
         * attribute value that contains entity references, the user must create 
         * an <code>Attr</code> node plus any <code>Text</code> and 
         * <code>EntityReference</code> nodes, build the appropriate subtree, 
         * and use <code>setAttributeNodeNS</code> or 
         * <code>setAttributeNode</code> to assign it as the value of an 
         * attribute.
         * <br>HTML-only DOM implementations do not need to implement this method.
         * @param namespaceURIThe namespace URI of the attribute to create or 
         *   alter.
         * @param qualifiedNameThe qualified name of the attribute to create or 
         *   alter.
         * @param valueThe value to set in string form.
         * @exception DOMException
         *   INVALID_CHARACTER_ERR: Raised if the specified qualified name 
         *   contains an illegal character.
         *   <br>NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
         *   <br>NAMESPACE_ERR: Raised if the <code>qualifiedName</code> is 
         *   malformed, if the <code>qualifiedName</code> has a prefix and the 
         *   <code>namespaceURI</code> is <code>null</code>, if the 
         *   <code>qualifiedName</code> has a prefix that is "xml" and the 
         *   <code>namespaceURI</code> is different from "
         *   http://www.w3.org/XML/1998/namespace", or if the 
         *   <code>qualifiedName</code> is "xmlns" and the 
         *   <code>namespaceURI</code> is different from "
         *   http://www.w3.org/2000/xmlns/".
         * @since DOM Level 2
         */
        void setAttributeNS(String namespaceURI,
                                   String qualifiedName,
                                   String value);//                               throws DOMException;

        /**
         * Removes an attribute by local name and namespace URI. If the removed 
         * attribute has a default value it is immediately replaced. The 
         * replacing attribute has the same namespace URI and local name, as 
         * well as the original prefix.
         * <br>HTML-only DOM implementations do not need to implement this method.
         * @param namespaceURIThe namespace URI of the attribute to remove.
         * @param localNameThe local name of the attribute to remove.
         * @exception DOMException
         *   NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
         * @since DOM Level 2
         */
        void removeAttributeNS(String namespaceURI,
                                      String localName);//                                  throws DOMException;

        /**
         * Retrieves an <code>Attr</code> node by local name and namespace URI. 
         * HTML-only DOM implementations do not need to implement this method.
         * @param namespaceURIThe namespace URI of the attribute to retrieve.
         * @param localNameThe local name of the attribute to retrieve.
         * @return The <code>Attr</code> node with the specified attribute local 
         *   name and namespace URI or <code>null</code> if there is no such 
         *   attribute.
         * @since DOM Level 2
         */
        Attr getAttributeNodeNS(String namespaceURI,
                                       String localName);

        /**
         * Adds a new attribute. If an attribute with that local name and that 
         * namespace URI is already present in the element, it is replaced by 
         * the new one.
         * <br>HTML-only DOM implementations do not need to implement this method.
         * @param newAttrThe <code>Attr</code> node to add to the attribute list.
         * @return If the <code>newAttr</code> attribute replaces an existing 
         *   attribute with the same local name and namespace URI, the replaced 
         *   <code>Attr</code> node is returned, otherwise <code>null</code> is 
         *   returned.
         * @exception DOMException
         *   WRONG_DOCUMENT_ERR: Raised if <code>newAttr</code> was created from a 
         *   different document than the one that created the element.
         *   <br>NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
         *   <br>INUSE_ATTRIBUTE_ERR: Raised if <code>newAttr</code> is already an 
         *   attribute of another <code>Element</code> object. The DOM user must 
         *   explicitly clone <code>Attr</code> nodes to re-use them in other 
         *   elements.
         * @since DOM Level 2
         */
        Attr setAttributeNodeNS(Attr newAttr);//                                   throws DOMException;

        /**
         * Returns a <code>NodeList</code> of all the descendant 
         * <code>Elements</code> with a given local name and namespace URI in 
         * the order in which they are encountered in a preorder traversal of 
         * this <code>Element</code> tree.
         * <br>HTML-only DOM implementations do not need to implement this method.
         * @param namespaceURIThe namespace URI of the elements to match on. The 
         *   special value "*" matches all namespaces.
         * @param localNameThe local name of the elements to match on. The 
         *   special value "*" matches all local names.
         * @return A new <code>NodeList</code> object containing all the matched 
         *   <code>Elements</code>.
         * @since DOM Level 2
         */
        NodeList getElementsByTagNameNS(String namespaceURI,
                                               String localName);

        /**
         * Returns <code>true</code> when an attribute with a given name is 
         * specified on this element or has a default value, <code>false</code> 
         * otherwise.
         * @param nameThe name of the attribute to look for.
         * @return <code>true</code> if an attribute with the given name is 
         *   specified on this element or has a default value, <code>false</code>
         *    otherwise.
         * @since DOM Level 2
         */
        bool hasAttribute(String name);

        /**
         * Returns <code>true</code> when an attribute with a given local name and 
         * namespace URI is specified on this element or has a default value, 
         * <code>false</code> otherwise. HTML-only DOM implementations do not 
         * need to implement this method.
         * @param namespaceURIThe namespace URI of the attribute to look for.
         * @param localNameThe local name of the attribute to look for.
         * @return <code>true</code> if an attribute with the given local name 
         *   and namespace URI is specified or has a default value on this 
         *   element, <code>false</code> otherwise.
         * @since DOM Level 2
         */
        bool hasAttributeNS(String namespaceURI,
                                      String localName);

    }
}